Section1 (2-1) Earth's Crust in Motion

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Vocabulary

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earthquake- the shaking and trembling that results from the movement of rock beneath the Earth's surface
stress- a force that acts on rock to charge its shape or volume
shearing- stress that pushes a mass of rock in two opposite directions
tension- pulls in a crust, streching the rock so that it becomes thinner in the middle
compression- squeezes rock until it folds or breaks
deformation- any change in the volume or shape of Earth's crust
fault- a break in earth's crust where slabs of crust slip past each other
strike-slip fault- the rock on either side of the fault slip past each othersideways with little up-or-down motion
normal fault- the fault is at angle, so one bolck of rock lies above the fault while the other block lies below the fault
hanging wall- the half of the fault that lies above
foot wall- the half of the fault that lies below
reverse fault- has a same structure as a normal fault, but the rocks move in opposite direction
folds- bends in rock that form when compression shortens and thickens part of Earth'sw crust
anticline- a fold in rock that bends upward into an arch
syncline- a fold in rock that bends downward
plateau- a large area of flat land elevated high above sea level

Outline

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Stress in the Crust

• The movements of earth's crust creates a powerful force
  • The force squeeze, or pull rocks in the crust
    • three forces are examples of stress
• Stress can change the volume, or the shape of the rock

Type of stress

• There are three types of stress
  • shearing
    • Shearing pushes rock in two opposite directions
    • It can cause rock to break, slip apart, and change its shape and volume
  • tension
    • tension pulls crust, and streches rock

• deformation
  • Deformation is a any change in volume, or shape in Earth's crust

Kinds of faults

• Strike- slip fault
  • shearing creates this fault
  • the rocks on each side of the fault slip past each other
  • strike- slip fault is same as transform boundry
• Normal fault
  • tension creates this fault.
  • The normal fault is at the angle.
  • Foot wall is on the top and hanging wall lies below.
  • The hanging wall slips downward and foot wall goes up.
• Reverse fault

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** Compression creates the reverse fault.

• It is same structure as the normal fault, but the hanging wall goes up and foot wall slips downward.

Friction Along faults

• Fault has low friction and rocks on either side slide past each other.
• If it is high friction, rocks on either side don't move.

Mountain Building

• Some of the mountains are formed by faulting.
  • Normal fault uplifts the rock and the fault- block mountain forms.
    • Fault block mountain forms
• Mountains are created by the folding of the rock
  • mountains are made by compression
• Anticline and Synclines
  • anticlines fold upward
  • synclines fold downward
• Plateaus
  • are elevated high above sea level
  • a large are of flat land

Diagram of normal fault

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